In most homes and buildings, heating and cooling is controlled by a thermostat. Typically, the occupant sets the thermostat to a desired temperature. The thermostat maintains the desired temperature by controlling the heating and cooling equipment. Conventional thermostats maintain the temperature setting whether or not a person is present in the room or building.
There will be instances where the occupant will leave the room or building for a period of time. When the occupant has left the room or house it is not necessary to maintain the temperature setting of the thermostat. Since heating and cooling is a major expense in maintaining most buildings, it is desirable to monitor the presence or absence of the occupant and to set back or reduce the heating (and cooling) output when the occupant is away from the building.
There are systems which set back the temperature when the occupant has left the room. These systems typically employ a motion sensor to detect the occupant's presence. When the occupant leaves, the system sets the temperature back to a first set-back. The first set-back temperature is typically such that the room temperature can be returned to the desired setting within a few minutes of the occupant returning. If the occupant is absent for a long period of time, the system sets the temperature to a second set-back which is usually considerably below the desired temperature. The problem with this system is that if the occupant returns the system will require a substantial period to restore the desired temperature because of the thermal inertia. For seasonal dwellings used infrequently, such as cottages and ski chalets, it may take many hours to restore the temperature to the comfort level desired by the occupants.
Clearly, it is desirable to have a system for controlling heating and cooling which provides for energy savings by setting back when the room or building is unoccupied. Accordingly, the present invention provides a heating control system which will set back the heating and cooling equipment when the room or building is unoccupied, and which will allow the heating and cooling equipment to be controlled by telephone from a remote location.